In the treatment of various cancers, and in particular prostate cancer, a process called brachytherapy has proved effective. In brachytherapy, small capsules containing radioactive material are implanted in or near to the tumour.
One known form of capsule or canister, commonly used to treat prostate cancer and referred to as a “seed”, is shown in FIG. 7. The capsule 100 comprises a silver rod 102, coated with a radioactive isotope of iodine such as I-125, inside a hollow titanium tube 104. The ends of the tube are welded closed. Resin balls coated with radioactive iodine can be used instead of the silver rod 102. The completed capsule has a width of approximately 1.0 mm and a length of approximately 4.5 mm. The capsules or seeds can be implanted into a patient individually; alternatively, the capsules can be inserted into medical stitching material or suture, which is then inserted into the prostate and left there.
The number of capsules implanted into each patient obviously varies in accordance with the regime of treatment required, but is commonly in the region of 50 to 100. The capsules are normally made by hand, with the welding process used to close the ends of the tube being carried out manually. It will be appreciated that making such a large number of capsules for each patient by hand takes considerable time and expense.